DP Chemistry (last assessment 2024)

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Question 19M.1.hl.TZ2.20

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Date May 2019 Marks available [Maximum mark: 1] Reference code 19M.1.hl.TZ2.20
Level hl Paper 1 Time zone TZ2
Command term Question number 20 Adapted from N/A
20.
[Maximum mark: 1]
19M.1.hl.TZ2.20

Which statement is correct about a catalyst?

A. It decreases the activation energy of the forward reaction but not the reverse.

B. It increases the proportion of products to reactants in an equilibrium.

C. It decreases the enthalpy change of the reaction.

D. It changes the mechanism of the reaction.

[1]

Markscheme

D

Examiners report

This was surprisingly one of the most challenging questions on the paper and discriminated very well between high scoring and low scoring candidates. It tested understanding of the role of the catalyst. 52 % of candidates chose the correct answer (a catalyst changes the mechanism of the reaction). The most commonly chosen distractor was A (a catalyst decreases the activation energy of the forward reaction but not the reverse).

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